The invention relates to skateboards used for recreational and personal transportation and which are powered by the rider's feet.
Prior to this invention, the steering of skateboards was controlled by the rider shifting his weight from side to side. As the rider shifted his weight to one side the geometry of the wheel trucks, the skateboard's suspension system, is altered causing the axles and wheels of the trucks to change their orientation. While various methods of controlling a skateboard's wheel trucks, and hence the path followed by the skateboard, have been devised and are commercially available, all such systems rely upon the shifting of the rider's weight, and the attendant relocation of the force acting on the truck's wheels to turn the skateboard.
Skateboards using traditional steering methods suffer from several serious shortcomings. The technique employed by the rider for turning the skateboard is an unnatural one and one not easily acquired by novices. Hence, new riders frequently suffer falls while attempting to negotiate turns. Moreover great numbers of potential skateboard riders are dissuaded from using skateboards because of the difficulty they envision they will experience in learning to negotiate turns on a skateboard.
Another problem encountered relates to the methods which riders must use to increase the amount of a turn. Riders increase the rate of turn by increasing the amount of weight they place on the outside wheels through concerted leaning into a turn. Unfortunately, such leaning can cause the rider's center of gravity to move outside the center of force acting on the wheels and result in the upsetting of the skateboard.
Still another disadvantage of presently available skateboards is their lack of any accommodation for the rider other than a platform on which the rider must stand. When the skateboard is used as a means of personal transportation, it is highly desirable that a seat be provided so that the rider need not remain on his feet for the entire journey.
A final shortcoming of the present skateboards is that there is no means for locomotion other than pushing with one's foot. While foot propulsion is simple and convenient, it lacks any method for providing a mechanical advantage to the rider or operator. Moreover, as the rider pushes the board with one foot, his center of gravity is constantly changing. Skateboard riders of all levels of experience have allowed their center of gravity to move, while they are propelling the board, outside of the boundary of stability with the result that the board upsets.